This document discusses abnormal or anomalous secondary growth in plants. It defines secondary growth as an increase in plant girth due to vascular cambium or cork cambium. Anomalous secondary growth does not follow the normal pattern of a single vascular cambium producing xylem internally and phloem externally. Some examples given of plants that exhibit anomalous secondary growth include Bougainvillea, which forms multiple cambium rings outside the oldest phloem, and monocots like Dracaena which can exhibit secondary growth in roots. The document also describes different types of anomalous secondary growth that can occur in dicot stems due to abnormal cambium position or activity.

1. Abnormal
Secondary Growth
PREPARED BY:AZKA JAVED

2. Secondary Growth
 An increase in plant girth due to vascular cambium
or cork cambium is called secondary growth.

3. Secondary growth & lateral
meristems

4. Anomalous
 Whereas the development, arrangement, activity of
the vascular cambium in most woody
dicotyledonous and Gymnospermous plants tends
to be very similar, there are some alternatives which
produce new secondary tissues that do not follow a
normal pattern. As a result, the secondary plant
structures that are formed are termed anomalus.
Most anomalous growth is associated with the
formation of multiple cambia.`

5. Abnormal Secondary growth
 Abnormal secondary growth does not follow the
pattern of a single vascular cambium a thick hair clit
producing xylem to the inside and phloem to the
outside. Some dicots have anomalous secondary
growth, e.g. in Bougainvillea a series of cambia arise
outside the oldest phloem.

7. Abnormal growth in monocot
 Most monocots either have no secondary growth or
else anomalous secondary growth of some type;

8. Monocotyledons
Dracaena (the Dragon's blood tree) is the only monocot which has
been shown to also have secondary growth in roots.

9. Anomalous secondary growth in
dicot system
 Secondary growth in dicot systems characterized by
the following;

10.  By the formation of new cambium strips in the
interfascicular region by the initiation of
meristematic activity in the parenchymatous cells of
primary medullar rays adjacent to fascicular
cambium.
 These interfascicular cambium strips join with the
fascicular cambium to from a complete ring of
vascular cambium.
 Position of vascular cambium ring always lies
between the primary xylem and phloem.

11.  Cells of this cambium cut secondary xylem towards
inner side and secondary phloem towards outer
side.
 Normally single vascular cambium ring remains
active and no extra cambium rings are formed
except a ring of cork cambium which develops
extra stellar.

12.  Anomalous Secondary Growth: type of secondary
growth which deviates from the normal type is
regards as abnormal or anomalous secondary
growth.
 In Dicot stem anomalous secondary growth occurs
due to following reasons –
 Normal position of cambium with abnormal activity.
 Abnormal position of cambium with normal activity.
 Abnormal position of cambium with abnormal
activity

13. Abnormal secondary growth in
dicot stem
Cross section of Boerhaavia
stem, showing successive
rings of xylem and phloem

14. Abnormal secondary growth in
different plants
 Beta vulgaris root & stem.
Beta TS root

15. Abnormal secondary groth in
plants
 Bougainvillea is a member of the Nyctaginaceae
and is an example of a dicotyledonous stem which
displaysanomalous secondary growth. In this TS, near
the centre of the stem, you will see some primary
vascular bundles embedded in lignified pith
parenchyma. Move the slide towards the outer regions,
and you will notice that there has been fairly extensive
production of secondary vascular tissue. Look for
the vascular cambium. Secondary phloem and
secondary xylem lie on either side of it. The secondary
xylem is composed of tracheids, fibers and narrow-
diameter vessels. Interspersed with the secondary
xylem you will be able to see small pockets of phloem
and what look like large- diameter of metaxylum.

16. Daucus (carrot) root;
Carrot root

17. Campsis TS stem
Bougainvillea

18. 6. Serjania stem

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